1. Field of the Invention
The invention relates to an improvement of the productivity of a multichamber sputtering apparatus which is used for manufacturing a semiconductor device and the like.
2. Description of the Related Art
Film deposition techniques include vacuum evaporation, sputtering, chemical vapor deposition (CVD) and the like. In a process of manufacturing a semiconductor device, sputtering is frequently used to deposit a film for a wiring material and the like. In semiconductor devices such as a memory device and a logic device, as the degree of integration of such a device is increased and the performance is further improved, the request for improved reliability of the device is largely expanding. In order to meet the request, wiring processes by sputtering and the like have been remarkably advanced.
Specifically, in order to improve the resistance to electro migration, AlSi which has been used as a wiring material is replaced with an AlSiCu material containing Cu. Furthermore, it has been requested to form a Ti/TiN lamination film as a diffusion barrier film (barrier film) for an underlying layer and a wiring layer, between an Si foundation and an AlSiCu wiring. A process of depositing a film of an Al wiring material on such a barrier film is enabled by a sputtering apparatus of the multichamber type in which different film depositing processes can be consistently conducted in a vacuum.
On the other hand, current semiconductor devices are highly integrated having narrow wiring patterns and many layers. Under this situation, a conventional sputtering technique has reached its limitation with respect to the film deposition of a barrier film and a wiring material in a fine hole. Therefore, various attempts to improve a sputtering method have been made. For sputtering of an Al wiring material, the high-temperature sputtering method has been developed. In this method, sputtering is conducted at a substrate temperature in the vicinity of the melting point of an Al material, whereby the Al material is caused to flow into a fine hole so as to realize the filling process.
According to the method, it is expected to apply a sputtering technique to a manufacture of a memory device of 64 to 256 Mbits, and further that of 1 Gbits in which the wiring width is 0.18 micron-meters.
In this way, a film deposition adapted to a high degree of integration of a device requires a sputtering method using a high-temperature process. However, such a method remains to have a problem from the viewpoint of productivity. Namely, the method has a problem in that the period required for a process of degassing a substrate before the high-temperature film deposition is to be shortened.
As described above, a high-temperature process for Al (400 to 500.degree. C.) uses the fluidity of Al. However, it is known that, when impurities such as water and oxygen molecules are deposited or precipitated on the surface of Al on the substrate during sputtering, the fluidity is largely impaired. The reduction of the impurity level during Al sputtering is a very important technique. To comply with this, water and oxygen molecules which may separate from the substrate during sputtering must be previously removed away by heating the substrate before the high-temperature film deposition of Al. Consequently, a process called degas is essential.
During the degas process, the temperature of the substrate must be higher than that during the high-temperature film deposition of Al, because of the following reason. When the degas temperature is lower than the temperature during the high-temperature film deposition of Al, the impurities are released from the substrate into the Al film during the deposition of the Al film, and hence the fluidity of Al is largely impaired, so that the filling process is not accomplished.
Because of the above-mentioned reason, usually, the degas temperature is set to be at a sufficiently high temperature or 450 to 600.degree. C. From the viewpoint of productivity, however, a high degas temperature produces a problem of a very low efficiency because of the following reason. A process in-which the temperature of the substrate is raised to the above-mentioned high value and maintained to this value to sufficiently degas requires a prolonged period, with the result that the productivity as a whole is lowered.